Synergistic interaction of thymol with Piper ribesioides (Piperales: Piperaceae) extracts and isolated active compounds for enhanced insecticidal activity against Spodoptera exigua (Lepidoptera: Noctuidae)

Chemical and Biological Technologies in Agriculture

Table 3 Potential toxicity due to binary mixtures of thymol and isolated compound of P. ribesioides extracts against 2nd instar S. exigua after 24 h

Compound A	Compound B (P. ribesiodes extracts in respective solvents)	Sublethal dose (µg/larvae)	Laval mortality (%)				χ²	Effect
			Pure compounds		Binary mixtures
			Observed A	Observed B	Expected	Observed
Piperine (LD₁₀)	Thymol (LD₁₀)	0.04 + 1.21	13.33	13.33	24.31	30.00	1.33	Additive
Piperine (LD₁₀)	Thymol (LD₃₀)	0.04 + 9.54	13.33	16.67	27.79	56.67	30.01	Synergistic
Piperine (LD₃₀)	Thymol (LD₁₀)	0.16 + 1.21	16.67	13.33	27.79	53.33	23.47	Synergistic
Piperine (LD₃₀)	Thymol (LD₃₀)	0.16 + 9.54	16.67	16.67	31.11	10.00	14.32	Antagonistic
Phenethylcinnamamide (LD₁₀)	Thymol (LD₁₀)	0.13 + 1.21	23.33	13.33	33.01	53.33	12.51	Synergistic
Phenethylcinnamamide (LD₁₀)	Thymol (LD₃₀)	0.13 + 9.54	23.33	16.67	36.09	46.67	3.10	Additive
Phenethylcinnamamide (LD₃₀)	Thymol (LD₁₀)	0.36 + 1.21	30.00	13.33	39.10	63.33	15.02	Synergistic
Phenethylcinnamamide (LD₃₀)	Thymol (LD₃₀)	0.36 + 9.54	30.00	16.67	41.90	33.33	1.75	Antagonistic
Cinnamic acid (LD₁₀)	Thymol (LD₁₀)	0.11 + 1.21	6.67	13.33	19.09	40.00	22.90	Synergistic
Cinnamic acid (LD₁₀)	Thymol (LD₃₀)	0.11 + 9.54	6.67	16.67	22.81	16.67	1.65	Additive
Cinnamic acid (LD₃₀)	Thymol (LD₁₀)	0.39 + 1.21	26.67	13.33	36.49	60.00	15.15	Synergistic
Cinnamic acid (LD₃₀)	Thymol (LD₃₀)	0.39 + 9.54	26.67	16.67	39.41	36.67	0.19	Antagonistic